This invention relates to a mining tooth point and, more particularly, to a point that is more easily installed on but more difficultly removed from the supporting adapter.
Notwithstanding subsequent tooth developments in the form of co-owned Pat. No. 4,231,173 (the SUPER CONICAL.RTM.) and No. 4,335,532 (the HELILOK.RTM.), the tooth that has remained the standard for mining is the No. 77 CONICAL.RTM.. This tooth is a combination of co-owned Pat. Nos. 2,919,506 and 3,079,710 and employs a pin lock of the type seen in Pat. No. 3,126,654.
The designation 77 relates to the fact that the horizontal dimension of the tooth point socket measures 7.7 inches at the conical axis adjacent the rear of the point. The principal problem with these points is the difficulty of installing the locking pin. The problem is not so severe in some instances with the smaller teeth and the larger teeth employ a spool and wedge.
The point and adapter nose have aligned vertically extending openings into which a "corrugated" pin is installed--to cooperate with a complementary rubber lock or keeper. A frequent experience has been that the strongest man in the shift equipped with a heavy sledge has extreme difficulty in driving the locking pin to final assembly. It should be appreciated that these teeth parts are quite heavy, the point weighing upwards of 100 pounds and the adapter upwards of 400 to 500 pounds. Replacement is often performed under arduous conditions in the field. It also will be appreciated that the points wear rapidly and require replacement. Depending upon the abrasiveness of the material being excavated, a point may last from a matter of hours to a matter of days or weeks. In any event, there is relatively frequent replacement--at least in terms of the adapter life. Normally an adapter will last from about 5 to about 30 replacement points.
The problem of installation has been solved by the instant invention through the use of a pair of novel shaped pin-receiving openings in the point which accommodate the receipt of a complimentarily shaped pin. More particularly, the rear generally vertical walls of the point pin openings have been changed from being co-planar to now being each outwardly convergent with its associated pin opening front wall.
This makes use of a pin with a corresponding inclination making possible (a) more offset between the inner ends of the point opening rear walls and the nose opening rear wall than the offset characteristic of the same tooth according to the prior art having vertical rear walls in the point openings, thereby providing more takeup of the point on the adapter nose; (b) less interference in installation, and (c) increased bearing area between the pin and point opening rear walls.
Pertinent art are Pat. Nos. 4,182,058 and 4,455,771 which show an inclined rear wall in one of the point pin opening but for a different purpose.